Dust collector



Sheet 1 0:55

Jan. 7, 1969 R, E, N-EELY 'ETAL DUST COLLECTOR Original Filedfipril 21, 1961 I CL EAN GAS our I fill/11111!!! I!!! ///l/ 1/! I! I I I I l I I 1 I I I I I l I I I ROBERT E. NEELY ALEX. o. LIMONOZENKO INVENTORS ATTORNEYS-..

J II n U =1 Wa a H H J\ Jan. 7 1969 R. E. NEELY ETAI- DUST COLLECTOR Sheet 2 of 5 Original Filed April 21, 1961 ROBERT E.- NEELY ALEKSEJ. 0. umouczsuxo INVENTORS ATTORNEYS.

Jan; 7, 1969 V R NEELY ETAL 3,420,040

DUST COLLECTOR Ori inal Filed April 21, 1961 Sheet 3 of 5 ROBERT E. NEELY" ALEKSEJ D.-l |MONCZENKO INVENTORS ATTORNEY United States Patent 3,420,040 DUST COLLECTOR Robert E. Neely and Alex D. Limonczenko, Los Augeles,

'Calif., assignors to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Continuation of application Ser. No. 112,147, Apr. 21, 1961. This application June 22, 1965, Ser. No. 468,672 U.S. Cl. 55346 14 Claims Int. Cl. B01d 45/12 This application is a continuation of application Ser. No. 112,147 (now abandoned) filed Apr. 21, 1961, which was a continuation-in-part of application Ser. No. 762,836 filed Sept. 23, 1958, now abandoned.

The present invention relates generally to apparatus for the separation of suspended particles by centrifugal action from a stream of gas in which the particles are carried, and more particularly to improvements in the design of the individual cyclonic units in multiple unit devices of this character.

It is well known that a cyclonic unit of relatively small diameter is more efficient in separating suspended particles than is one of relatively large diameter, because for a given gas velocity within the separating tube, the forces acting on dust particles are inversely proportional to the diameter of the tube. Since the purpose of these units is to remove the maximum possible amount of the material suspended in the gas stream, much effort has been directed toward the improvement of the collecting efficiency of the units. Some prior designs achieve a relatively high collection efficiency with a reduction in the maximum gas flow rate which is attained through the particular cyclonic unit for a given pressure drop across the unit. Such decrease in the maximum attainable gas flow rate through a unit of given diameter is not always acceptable, even at the higher collection efiiciency, because the number of such units must be increased, to process a given volume of gas at a specified rate of flow, with a consequent increase in the cost of the complete dust collector.

Accordingly, a general object of this invention is to provide a cyclonic unit of the character described which, under given conditions, obtians both maximum collection efliciency and maximum rate of gas flow through the unit.

The general object of this invention, differently stated, is to increase the rate of gas flow through a cyclonic unit of high efiiciency and/ or improve the efliciency without any significant increase in the pressure drop between the inlet and the outlet of the unit.

These and other objects of this invention have been achieved in a cyclone type dust collector having cyclonic units each of which includes a separating tube provided with gas inlet in one end and with spin-producing means inwardly adjacent said inlet which impart a whirling motion to the entering gas stream. The cyclonic unit also has a clean gas outlet tube which extends into the separating tube at the inlet end and is positioned coaxially with the separating tube, the cleaned gas leaving the unit through this outlet tube. In one embodiment of this invention a formed generally tubular sleeve, open at both ends, is mounted on the clean gas outlet tube, and is located coaxial with the inner end of the outlet tube so that it forms an extension thereof. This tubular extension sleeve is of lesser diameter than the outlet tube and may be frusto-conical, or of any suitable airfoil shape to insure a directed flow of gas. Being of smaller diameter than the outlet tube, the extension sleeve defines with the outlet tube a first outlet opening for cleansed gas, which opening is of annular shape and located at the inner end of the outlet tube. The sleeve also defines a second outlet opening for clean gas at the innermost end of the extension more remote from the outlet tube. A plurality of 3,420,040 Patented Jan. 7, 196 9 straightening vanes of spiral configuration are mounted upon, and extend axially from, the innermost end of the tubular sleeve to engage the swirling gas stream as it approaches the innermost open end of the sleeve forming the second gas outlet opening.

The objects of this invention have also been achieved in another embodiment wherein a similar punpose cyclonic unit differs from the above described embodiment in that a plurality of axially spaced frusto-conical tubular sleeve extension-s are provided at the inner end of each clean gas outlet tube. The sleeves are positioned coaxial with the outlet tube and each sleeve has the smaller diameter end thereof, nearest the outlet tube. With such structure a plurality of outlet openings are provided for the cleansed gas. In the embodiment described hereinafter, three such tubular sleeves define a first, a second and a third cleansed gas opening and the innermost larger diameter end of the sleeve most remote from the outlet tube defines a fourth clean gas outlet.

How the above objects and advantages of our invention, as well as others not specifically mentioned herein, are attained will be more readily apparent from the following description and the annexed drawings in which:

FIG. 1 is a side elevation of a complete dust collector comprising a plurality of cyclonic units designed to operate in parallel.

FIG. 2 is an enlarged vertical median section through one of the cyclonic units, as on line 22 of FIG. 1.

FIG. 3 is a fragmentary perspective view at a further enlarged scale of an upper portion of the cyclonic unit shown in FIG. 2.

FIG. 4 is a horizontal sectional view taken substantially on line 4-4 of FIG. 3.

FIG. 5 is a horizontal sectional view taken substantially on line 5-5 of FIG. 3.

FIG. 6 is a fragmentary view, similar to FIG. 3 of an enlarged vertical median section through a cyclonic unit with another embodiment of this invention therein.

FIG. 7 is an enlarged horizontal section taken substantially on line 77 of FIG. 6.

A complete dust collector is shown in FIG. 1 which is but one of the many possible different designs. The collector comprises a suitable rectangular housing 10 mounted on a suitable angle iron framework that includes four supporting legs 11. The housing 10 may be made of metal sheets forming two spaced side walls 12 connected at their vertical edges by front and rear walls 13 and 14 respectively. The sheets forming these walls of the housing may be interconnected and reinforced in any suitable manner, as by braces 17, and angles 19 and other members which are not shown since they are not necessary to an understanding of the present invention.

Housing 10 has a rectangular gas inlet 26 in front wall 13, the opening being surrounded by an angle iron frame 24 providing a flange to which suitable duct work (not shown) may be connected. A similar fiange 25 is provided at the top of the housing to define an outlet opening to which other duct work may be connected to convey away cleansed gas. Alternately, the outlet defined by flange 25 can be in the vertical side wall 14. In either case, the outlet opening from the housing 10 can vent directly to the atmosphere.

Inside housing 10, a horizontally disposed plate 28, commonly referred to as a tube sheet, divides the space within the housing. The space below plate 28 is the hopper space within which the dust is collected, this space extending downwardly and into the pyramidal hopper 22. Dust is discharged from the bottom of the hopper through outlet 23 by any suitable valve, not shown. Above tube sheet 28 the space within the housing 10 is divided by inclined plate 29 extending between side walls 12, and between walls 13 and 14, into a gas inlet chamber 30 impart a spinning motion to the gas as it enters each of A the separating tubes 36. Separating tubes 36 are normally arranged with their longitudinal axes parallel and in a substantially vertical position and for this reason they are shown and described in this position. It will be understood that the invention is not necessarily limited thereby as the tubes 36 in horizontal or inclined positions would be within the scope of this invention. Each tube 36 is open at its upper end to receive from the gas inlet chamber 30 a stream of gas, carrying particles suspended therein which are to be separated from the gas. The opening in the upper end of each tube 36 is aligned with a similar opening 36b in tube sheet 28. Each separating tube 36 is suitably secured to the tube sheet 28 such as by a plurality of bolts 40.

Each separating tube 36 is also open at the lower end at 26:: to discharge dust particles, separated from the gas stream, which fall into hopper 22. Tubes 36 can be cylindrical for their full lengths, or preferably, taper downwardly from the intermediate portions to the lower ends thereof, as shown.

The vanes 38 are located inwardly adjacent the inlet end of each tube 36, and are formed integrally with a tubular collar 39, circumferentially secured on the outlet tube 37, by which the vane assembly is mounted in place. The entering gas stream impinges against vanes 38 which give to the gas stream a whirling motion which separates the suspended particles from the gas. Alternatively the gas may be introduced tangentially by an involute type of inlet, such as those shown by Patents Nos. 1,930,806 and 1,990,943 issued to G. H. Home et al., which gives a whirling motion to the gas stream.

Olean gas is exhausted from each separating tube 36 through the cylindrical outlet tube 37 which extends into the separating tube 36 at the inlet end and is positioned coaxially with the separating tube 36. Clean gas outlet tube 37 is open at both ends. The upper ends of all of the outlet tubes open into the gas outlet chamber 31 from which the clean gas is discharged from the housing through the gas outlet defined by the flange 25.

The structure of the cyclonic units so far described is old and well known in the art. This invention has improved their operation by the addition thereto of a formed tubular sleeve 42 which, as shown, is mounted on the lower or inner end of the clean gas outlet tube 37 coaxially thereof, by means of a plurality of suitable radial circumferentially spaced arms 42a. Mounted on the lower end of sleeve 42, which is the end remote from the inner or lower end of the outlet tube 37, is a plurality of circumferentially spaced spiral vanes 43 which extend below the open end of sleeve 42. In the embodiment shown in FIGS. 1 to the tubular sleeve 42 is of a frustoconical shape, with its maximum diameter smaller than but substantially equal to the diameter of the outlet tube 37. The smaller end of the sleeve 42 is uppermost or adjacent to the inner end of the outlet tube 37 and is preferably near or substantially in the same plane as the opening at the inner or lower end of tube 37. The annular space between the sleeve 42 and the outlet tube 37 permits a portion of the cleansed gas to enter directly the open portion of the inner end of the outlet tube 37 as indicated by arrows 45.

Sleeve 42 is open at both ends. Clean gas can also enter the lower end, flow upwardly through the sleeve 42 and thus enter interiorly of the outlet tube 37. Vanes 43 are designed to reduce the spinning movement of the gas stream and cause the cleansed gas stream to enter the sleeve 42 with its motion primarily in a direction parallel to the axis of the separating tube 36. Vanes 43 convert a portion of the rotational energy into translational energy, reducing the total energy required to move gas through the unit. For this purpose vanes 43 are more efiicient when they have a spiral configuration and are inclined in a direction opposite to vanes 38. The number of flow straightening vanes is not critical but three or four are preferred in constructions wherein straightening vanes are preferred.

As may be seen by reference to FIG. 4, the outer curved edge of each vane 43 has a constant radius about the axis of the separating tube 36 so that the axial projection of the outer edge is a circular arc. The inner edge of each vane 43 starts at this axis and recedes farther away from the central axis as a point on this edge moves from the upper edge of the vane 43 to the lower edge. The shape of the curve of the inner edge is not critical. Thus each vane 43 may be defined generally as being of progressively decreasing radial width toward the lower end. At the upper end, each vane 43 has a width equal to the internal radius of the adjoining end of outlet sleeve 42 so that the vanes 43 meet each other substantially on the axis of the separating tube 36 and extend radially outwardly to sleeve 42. The vanes 43 are welded together where they meet and are welded to the sleeve 42 in a preferred construction, but other suitable fastening means may be used.

The incoming gas stream flows through inlet chamber 30 with portions thereof flowing into the upper end of each of the cyclonic units 35, as is well known and as indicated by arrows 46. Upon entering a separating tube 36, the gas stream strikes against vanes 38 which give the gas stream a spinning motion about the axis of tube 36. As a consequence each portion of the entire gas stream moves in a spiralling downwardly path (counterclockwise with reference to FIG. 5) within a separating tube 36. Such spinning motion causes a centrifugal force to be exerted upon the suspended particles in the gas stream that moves the particles radially outwardly in the gas stream to the outer periphery of the stream so that the particles are concentrated in a layer of gas immediately adjacent the inner surface of the tube 36.

After each portion of the gas stream flows downwardly from a set of vanes 38 such portion is confined between a separating tube 36 and an outlet tube 37 until it passes the inner end of the outlet tube 37. After such flow an initial portion of such flow immediately adjacent the outer surface of the outlet tube 37 has been cleaned due to the centrifugal forces acting on the entrained particles, which cleansed portion is of increasing radial thickness outwardly from the outer surface of the tube 37 as the gas stream progresses downwardly from the vanes 38 to the inner end of the tube 37. When the gas stream passes downwardly beyond the inner open end of the tube 37 the lateral cross sectional area of the gas flow path increases so that the velocity of the gas stream decreases and the static pressure of the gas stream increases. In view however, of the downstream divergence of the outer surface of the sleeve 42, the lateral cross sectional area of the gas flow path below the inner end of the tube 37 gradually decreases whereby the velocity of the gas stream gradually increases as it flows downwardly beside the sleeve 42 and the static pressure gradually decreases. Due to such decrease in velocity and increase in static pressure at the inner end of the tube 37 such initially cleansed portion, or the greater portion thereof, of the gas stream enters the tube 37 at the inner end. It will be appreciated that a minimum of turbulence in the portion of the gas stream entering the inner end of the tube 37 is desired in order to reduce the pressure drop in the system, accordingly, the sleeve 42 is provided with an outer surface which directs the initially cleansed portion of the gas stream to provide as smooth flow as possible. For such purposes the truncated conical sleeve 42 as described has been found to be satisfactory; however, it is to be realized that the outer surface of the sleeve 42 can be of various configurations, such as an airfoil section, to so direct the initially cleansed portion of the gas stream entering the inner end of the tube 37. The portion of the total gas stream entering the inner end of the outlet tube 37 is also controlled in part by the size of the annular opening between the outlet tube 37 and the sleeve 42, most favorable operation has been found to occur when the diameter of the sleeve 42 at the end adjoining the outlet tube 37 is within the range of one-half to three-fourths of the diameter of the outlet tube 37. Thus the radial width of the annular opening around the sleeve 42 is preferably within the range of one-fourth to one-eighth of the diameter of the outlet tube 37.

The remaining or uncleansed portion of the gas stream, its velocity gradually being increased, continues to spiral downwardly within the separating tube 36 until it reaches some position upwardly adjacent the open lower end 36a of the tube. After having so traversed downwardly of the tube 36 the static pressure of the gas stream decreases with the decrease in elevation and although rotating in the aforementioned counterclockwise direction, its direction of axial movement is reversed so that the gas stream spirals upwardly in the tube 36. The general movement of the gas stream in the tube 36 is indicated by the arrows 47 and 34 which illustrate an outer downward spiral and an inner upward spiral, respectively. It is to be realized that such reversal of the gas stream is accomplished in any well known manner such as by means of an exhaust fan or blower in the gas outlet defined by the flange 25.

Such spiralling downward of the gas stream causes the particles in the gas stream to be forced radially outwardly of the gas stream so that upon reversal of the axial movement of the gas stream the suspended particles in the lower portion of the separating tube 36 are carried into the hopper 22 peripherally through the opening 36a via small quantities of gas which in turn re-enter the tube 36 centrally through the opening 36a and mingle with the aforementioned upwardly spiralling gases. The upwardly spiralling portion of the gas stream impinges on the inner concave surface 43 of the vanes 43. The surface 43' has a reducing curvature from its lower edge upwardly, having the lower portion obliquely inclined downwardly in a clockwise direction (with reference to FIG. 5) so that the remaining spinning motion of the upwardly spiralling gas is transformed into axial motion as the gas enters the lower end of the sleeve 42. This lower end of the sleeve 42 forms an outlet from the separating tube 36 for the upwardly spiralling portion of the gas stream. The sleeve 42, being of frusto-conical configuration with decreasing cross sectional area in the direction of gas flow, directs the upward flow of gas with increasing velocity into the lower end of the outlet tube 37 where it joins the flow of the first or initially cleaned portion of the gas stream and all the cleansed gas is then discharged from the cyclonic unit through the upper end of the outlet tube 37. The inner surface of the sleeve 42 has been described as being of frusto-conical configuration in a preferred construction but it is to be realized that the inner surface of the sleeve 42 can be of various configurations such as an airfoil section to impart a smooth flow to the portion of the gas stream affected by it.

Sleeve 42 provides two separate outlets for cleansed gas from the separating tube 36, the upper annular one of which allows the initially cleansed portion of the gas to be discharged from the separating tube 36 as soon as practical, and before the remaining portion of the gas is cleansed. Mounting the straightening vanes 43 to extend below the sleeve 42 is preferred to mounting the vanes 43 upwardly in the sleeve 42 as at such position the vanes 43 reduce the spinning movement of the gas as soon as possible after the dust particles have been removed and transform such spinning movement into axial motion before the rotational energy of the gas has been dissipated by frictional contact with the inner surface of the sleeve 42, with a concurrent reduction in turbulence when this upward flowing portion of the gas stream joins with the first cleaned portion at the inner end of outlet tube 37. Thus the vanes 43 make more efficient use of the energy in the gas. The vanes 43 have been shown and described in a preferred construction, however, it will be appreciated that the vanes 43 can be omitted without departing from the scope and spirit of this invention. Thus, for example, some combinations of pressure drop and gas flow through the unit reduce the usefulness of the vanes 43 because, under such conditions there is little or no spinning movement remaining in the upwardly moving portion of the gas when it reaches the lower end of sleeve 42.

A comparison of the operation of a cyclonic unit of the prior art with one constructed according to the principles of this invention will reveal the following differences: the presence of the sleeve 42 on the lower end of the outlet tube 37 provides a means of separating the incoming downwardly spiralling stream of gas from the upwardly moving outgoing stream, to prevent mingling of the gaseous countercurrents whereby a much smoother flow of the gas stream is achieved than is achievable without such separation. Such separation of the gaseous streams increases the efficiency of the unit as compared to similar proposed units in which the gas streams are not so separated. The action of the straightening vanes 43, which transform rotational motion of the gas into axial motion in the desired direction outwardly through the sleeve 42 and the tube 37, reduces the presure drop through the unit by reducing the energy lost in the unit. Consequently the total gas gow which can be efficiently handled by a cyclonic unit of given dimensions constructed in accordance with the principles of this invention, and having a given pressure drop across it, is increased beyond that of a cyclonic unit of the prior art. The aforementioned increased gas flow with no increase in pressure drop across the unit will cause the downward spiralling steam of gas to penetrate more deeply into the separating tube 36 thus increasing the cleaning action by increasing the length of spiral path along which centrifugal forces can continue to act. In this way the sleeve and straightening vanes combine to achieve maximum collection efficiency with maximum gas flow.

FIGS. 6 and 7 show another embodiment of this invention in which the same numbers have been used to designate parts which are identical with those used in the hereinabove described embodiment. This embodiment differs from that first described in the following respects. The sleeve 42, mounted on the inner or lower end of the outlet tube 37, and the straightening vanes 43 (see FIG. 2) have been omitted and replaced by three identical axially alined frusto-conical tubular sleeve members 52, 53, and 54, being upper, middle and lower sleeve respectively, having their common axis coinciding with the axis of outlet tube 37. The frusto-conical sleeves'52, 53, and 54 are all similarly oriented having their smaller ends upward or nearest to the inner end of the outlet tube 37 and are axially spaced from each other and from the inner end of the outlet tube 37 by a distance shown as approximately equal to one-sixth, which fraction can vary from one-eighth to one-quarter, of the axial height of each frusto-conical sleeve for a purpose hereinafter to be described. The maximum diameter of each sleeve is smaller than, but substantially equal to, the inner diameter of the outlet tube 37. The upper sleeve 52 is rigidly secured, in axially spaced relationship to the innermost end of tube 37, by three mounting strips 56 rigidly engaged upon the outer surface of the sleeve 52 and the inner periphery of the outlet tube 37 as by welding. The two lower sleeves 53 and 54 are secured in axially spaced relationship to each other and to the upper sleeve 52 in a similar manner by mounting strips 55. The innermost end of the outlet tube 37 and the smaller end of the sleeve 52, adjacent thereto, define and inverted frusto-conical space 57, therebetween coaxial with the the outlet tube 37, having its upper base concentric with the innermost end of the outlet tube 37 and its lower base defined by the outer periphery of the smaller end of sleeve 52. This space 57 provides a first outlet for cleansed gas from the collector tube 35 by way of the outlet tube 37, space 57 being of appropriate size to properly control the amount of gas desirably flowing through this outlet. Similar spaces 58, 59 defined between the sleeves 52 and 53 and between the sleeves 53 and 54, respectively, provide a second outlet 58 and a third outlet 59 for cleansed gas from the separating unit 35 by way of the outlet tube 37. The larger end of the lower sleeve 54 is entirely open and provides a fourth outlet for the cleansed gas. Straightening vanes 43 are mounted on the lower end of sleeve 54 in the same manner as they are on the lower end of sleeve 42 in FIG. 2. If desired, straightening vanes 43 may be omitted in order to increase the cleaning etficiency of the apparatus.

The operation of the embodiment illustrated in FIGS. 6 and 7 is the same as that of the embodiments of FIGS. 15 excepting only that three successive small portions of the gas nearest the outlet tube 37 which is a first cleaned portion, are removed seriatim in the same manner as the single portion of the first cleaned gas was removed by the sleeve 42 of the above embodiment, from the main stream of gas. The remaining portion of the gas continues in spiral motion, in a manner hereinbefore described, into the lower portion of the collector tube 36 whence, freed of its suspended dust particles, it returns by the inner path 34 in an upward direction. The gas next passes upwardly through the open end of the lower sleeve 54, where the inner conical surface configuration of the sleeves controls the joining of the various stream of gas, in the manner hereinbefore described, to achieve the desired flow, out through the outlet tube 37. The sleeves 52, 53, 54 have been described as having a frusto-concial configuration both outwardly and inwardly, however, it is to be realized that various configurations such as air foil sections can be employed to impart a smooth flow to the portions of the gas affected by the sleeves 52, 53, 54.

The provision of three sleeves in this embodiment, compared to the single sleeve of the embodiment illustrated in FIGS. 15, adds to the cleaning efficiency of the unit by allowing a larger but closely controlled portion of the first cleaned gas, nearest the outlet tube, to be removed from the main stream and kept separate from the upwardly spiralling portion. When straightening vanes 43 are employed, rotational energy is largely transformed into translational energy and reduces the pressure drop through the unit or alternatively increases the amount of gas which can be efficiently cleaned by a cyclonic unit of given dimensions with a given pressure drop across it. A larger portion of the gas having been removed from the main stream of gas entering the Separating tube 36, its velocity, directed downwardly into the lower portion of the separating tube 36, is reduced and reversal of its axial direction of motion takes place at a point of lesser penetration into the separating tube 36 with a consequent additional reduction of pressure drop through the unit. Or alternatively a greater volume of gas may be processed at the original value of the pressure drop with a concurrently greater penetration of the downwardly spiralling portion of the gas stream into the lower portion of the separating tube 36 with a consequent increase in cleaning action as hereinbefore described.

It is to be noted that the addition of one or more conical sleeves 42 or 52, 53, 54 results mainly in increased cleaning efiiciency, while the addition of straightening vanes 43 reduces the pressure drop through the unit with some decrease in etficiency. It follows that a judicious use of a combination of these features will result in a device having both high cleaning efliciency and relatively low pressure drop.

It will be realized that various changes may be made in the exact shape and arrangement of the several parts of the assembly without departing from the spirit and scope of this invention and all such changes are considered to be within the scope of the appended claims.

What I claim is:

1. In a cyclone type dust collector having an elongated separating tube axially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube the im provement comprising, a first open ended tapered sleeve mounted at and concentrically of said one end, said first sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube, a second open ended tapered sleeve mounted at and concentrically of said larger end of said first sleeve, said second sleeve having it smaller end spaced radially inwardly from said larger end in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end and having its own larger end more remote from said outlet tube, and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane containing said one end to a transverse plane spaced axially from said larger end of said second sleeve in the same direction said larger ends are spaced from said one end.

2. A cyclone type dust collector as specified in claim 1 wherein the larger ends of said first and said second open ended tapered sleeves have respective outside diameters substantially equal to the outside diameters of said one end of said outlet tube.

3. In a cyclone type dust collector having an elongated separating tube axially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube and with spin producing means located between said tubes the improvement comprising, a first frusto-conical sleeve open at both ends mounted at and concentrically of said one end, said first sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube; a second frusto-conical sleeve open at both ends mounted at and concentrically of said larger end of said first sleeve, said second sleeve having its smaller end spaced radially inwardly from said larger end in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end and having its own larger end more remote from said outlet tube, and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane containing said one end to a transverse plane spaced axially from said larger end of said second sleeve in the same direction said larger ends are spaced from said one end.

4. In a cyclone type dust collector having an elongated separating tube axially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube and with spin producing means located between said tubes the improvement comprising, a first frusto-conical sleeve open at both ends mounted at and concentrically of said one end, said first sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube; a second frusto-conical sleeve open at both ends mounted at and concentrically of said larger end of said first sleeve, said second sleeve having its smaller end spaced radially inwardly from said larger end of said first sleeve in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end of said first sleeve and having the larger end of said sleeve remote from said outlet tube, a third frusto-conical sleeve open at both ends mounted at and concentrically of said larger end of said second sleeve, said third sleeve having its smaller end spaced radially inwardly from said larger end of said second sleeve in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end of said second sleeve and having the larger end of said third sleeve more remote from said outlet tube, and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane spaced axially from said larger end of said third sleeve in the same direction said larger ends are spaced from said one end.

5. A cyclone type dust collector as specified in claim 4 wherein the larger ends of said first, second and third frusto-conical sleeves have respective outside diameters substantially equal to the outside diameter of said one end of said outlet tube.

6. In a multiple outlet tube, cyclone type dust collector having a plurality of cyclonic units wherein each unit comprises an elongated separating tube axially disposed about an elongated cylindrical outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube the improvement consisting of, a single open ended tapered sleeve mounted at and concentrically of said one end, said sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube, and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane containing said one end to a transverse plane spaced axially from said larger end of said sleeve in the same direction said larger end is spaced from said one end.

7. A cyclone type dust collector as specified in claim 6 wherein the larger end of said tapered sleeve has an outside diameter substantially equal to the outside diameter of said one end of said outlet tube.

8. A cyclone type dust collector as specified in claim 6 wherein the larger end of said tapered sleeve has an outside diameter and an inside diameter substantially equal to the outside diameter and the inside diameter of said one end of said outlet tube respectively.

9. In a multiple outlet tube, cyclone type dust collector having a plurality of cyclonic units wherein each unit comprises an elongated separating tube axially disposed about an elongated cylindrical outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube and with spin producing means located between said tubes the improvement consisting of a single frusto-conical sleeve open at both ends mounted at and con-centrically of said one end, saidsleeve having its smaller end spaced radially inwardly from said one end of said outlet tube in a plane to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube, and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane containing said one end to a transverse plane spaced axialy from said larger end of said sleeve in the same direction said larger end is spaced from said one end.

10. In a multiple outlet tube, cyclone type dust collector having a plurality of cyclonic units wherein each unit comprises an elongated separating tube coaxially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube the improvement consisting of; a formed tubular sleeve having a larger end and a smaller end, said smaller end having an outside diameter in the range of /2 to of the inside diameter of said one end of said outlet tube, said sleeve being coaxial with said outlet tube and having said smaller end substantially coplanar with said one end to define therewith an annular opening and said tubular sleeve having its larger end outwardly more remote from said one end.

11. In a cyclone type dust collector having an elongated separating tube axially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube and with spin producing means located between said tubes the improvement comprising: a pair of similarly formed tubular sleeves each having a larger end and a smaller end, respectively; both of said sleeves being coaxial with said outlet tube with the first of said sleeves mounted at and concentrically of said one end of said outlet tube; said first sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube; and with the second of said sleeves mounted at and concentrically of said larger end of said first sleeve; said second sleeve having its smaller end spaced radially inwardly from said larger end of said first sleeve to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end and having its own larger end more remote from said outlet tube; and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane containing said one end to a transverse plane spaced axially from said larger end of said second sleeve in the same direction said larger ends are spaced from said one end.

12. In a cyclone type dust collector having an elongated separating tube axially disposed about an elongated outlet tube with one end of said outlet tube terminating intermediate the length of said separating tube and with spin producing means located between said tubes the improvement comprising: first, second and third formed tubular sleeves each having a smaller end and a larger end, respectively; said first, second and third sleeves being coaxial with said outlet tube; said first sleeve being mounted at and concentrically of said one end; said first sleeve having its smaller end spaced radially inwardly from said one end of said outlet tube to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said one end and having its larger end remote from said outlet tube; said second sleeve mounted at and concentrically of said larger end of said first sleeve; said second sleeve having its smaller end spaced radially inwardly from said larger end of said first sleeve to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end of said first sleeve and having the larger end of said second sleeve remote from said outlet tube; said third sleeve mounted at and concentrically of said larger end of said second sleeve; said third sleeve having its smaller end spaced radially inwardly from said larger end of said second sleeve to define therewith an opening of annular shape substantially in a plane transverse to the axis of said outlet tube at said larger end of said second sleeve and having the larger end of said third sleeve more remote from said outlet tube; and said separating tube having a substantially constant internal cross sectional area extending at least from a transverse plane spaced axially from said larger end of said third sleeve in the same direction said larger ends are spaced from said one end.

13. A cyclone type dust collector as specified in claim 12 wherein the said smaller ends of said formed tubular sleeves have respective outside diameters in the range of /2 to of the inside diameter of said one end of said outlet tube.

14. A cyclone type dust collector as specified in claim 12 wherein said smaller end of said first sleeve is axially spaced outwardly from said one end of said outlet tube and said smaller end of said second sleeve is axially spaced outwardly from said larger end of said first sleeve and said smaller end of said third sleeve is axially spaced outwardly from said larger end of said second sleeve.

References Cited UNITED STATES PATENTS 408,907 8/1889 Woodbury 55445 648,225 4/1900 Wiman 9864 940,827 11/1909 Sheward 55410 X 1,509,910 9/1924 Stebbins 55291 1,541,337 6/1925 Feix 554l3 X 1,669,417 5/1928 Le Grand 55319 1,913,115 6/1933 Guest 554l3 X 2,370,444 2/1945 Bowman 55436 X FOREIGN PATENTS France. France. France. France. Germany. Germany. Germany. Great Britain. Great Britain. Great Britain. Great Britain.

U.S. Cl. X.R. 

1. IN A CYCLONE TYPE DUST COLLECTOR HAVING AN ELONGATED SEPARATING TUBE AXIALLY DISPOSED ABOUT AN ELONGATED OUTLET TUBE WITH ONE END OF SAID OUTLET TUBE TERMINATING INTERMEDIATE THE LENGTH OF SAID SEPARATING TUBE THE IMPROVEMENT COMPRISING, A FIRST OPEN ENDED TAPERED SLEEVE MOUNTED AT AND CONCENTRICALLY OF SAID ONE END, SAID FIRST SLEEVE HAVING ITS SMALLER END SPACED RADIALLY INWARDLY FROM SAID ONE END OF SAID OUTLET TUBE IN A PLANE TO DEFINE THEREWITH AN OPENING OF ANNULAR SHAPE SUBSTANTIALLY IN A PLANE TRANSVERSE TO THE AXIS OF SAID OUTLET TUBE AT SAID ONE END AND HAVING ITS LARGER END REMOTE FROM SAID OUTLET TUBE, A SECOND OPEN ENDED TAPERED SLEEVE MOUNTED AT AND CONCENTRICALLY OF SAID LARGER END OF SAID FIRST SLEEVE, SAID SECOND SLEEVE HAVING ITS SMALLER END SPACED RADIALLY INWARDLY FROM SAID LARGER END IN A PLANE TO DEFINE THEREWITH AN OPENING OF ANNULAR SHAPE SUBSTANTIALLY IN A PLANE TRANSVERSE TO THE AXIS OF SAID OUTLET TUBE AT SAID LARGER END AND HAVING ITS OWN LARGER END MORE REMOTE FROM SAID OUTLET TUBE, AND SAID SEPARATING TUBE HAVING A SUBSTANTIALLY CONSTANT INTERNAL CROSS SECTIONAL AREA EXTENDING AT LEAST FROM A TRANSVERSE PLANE CONTAINING SAID ONE END TO A TRANSVERSE PLANE SPACED AXIALLY FROM SAID LARGER END OF SAID SECOND SLEEVE IN THE SAME DIRECTION SAID LARGER ENDS ARE SPACED FROM SAID ONE END. 